This invention relates generally to the field of trailer electrical systems, and more particularly to a quick reliable power and/or data transfer system between tow vehicle and trailer via hitch and hitch receiver coupling.
There are many types of trailers in existence, such as cargo, camper and boat trailers. All of these types have at least one thing in common, they have a mechanical coupling called a hitch and hitch receiver. This mechanical coupling is the main load-bearing coupling connecting the tow vehicle to the trailer. One common type of hitch is the "ball type" hitch, whereby the hitch receiver slides over the ball and locks into place. Most often the hitch is mounted on the tow vehicle and the hitch receiver is mounted on the trailer, but this is not always the case. In the case of the tow vehicle being a large 18-wheeler type tractor, the hitch may be mounted on the trailer and the hitch receiver mounted on the tow vehicle. In many cases there will also be some type of safety connection to keep hold of the trailer in the event of the hitch and hitch receiver accidentally de-coupling during tow. These safety connections may consist of chains, bars and/or cables. Depending on the trailer and tow vehicle configuration, there may be other connections for that configuration. The most common additional connection would be air-brake hose couplings in the case of the tractor and trailer.
For safe operation, particularly for operation in low ambient lighting conditions, all vehicles in tow (read trailers) operated on public roadways should have brake lights, running lights and turn indicators. This trailer lighting subsystem necessitates the need for an electrical connection to exist between the tow vehicle and trailer. In addition there also exist trailers with electrical braking systems, which further necessitates the need for electrical connections to exist between the trailer to the tow vehicle. These electrical braking systems assist the tow vehicle's braking system and are typically found on camper type trailers and possibly large boat trailers.
The electrical connections between the tow vehicle and trailer are in the form of wiring harnesses and connector plugs. These harnesses carry several conductors to power the appropriate subsystem/indicator on the trailer. These wiring harnesses and connector plugs transfer electricity from the tow vehicle to the trailer. This type of electrical connection is mainly used to control the trailer lighting subsystem, but the same type of harness and connector is used to power a multitude of other subsystems, such as the electric brakes. Prior art has recognized that a complemental and/or supplemental system is needed for electrical interconnection between tow vehicle and trailer. This recognition stems from the desire to keep electrical wiring harnesses and plug connectors from growing too large in the number of conductors (wires), pins and complexity. One such prior complemental solution creates a data bus by sending/receiving data acoustically through the air-brake lines of a tractor-type tow vehicle and trailer. Another solution uses the electrical properties of the air-brake lines as an electrical conductor for a data bus. Yet another complemental solution utilizes existing dormant conductors in an existing harness and plug to create a data bus. These solutions utilize a microprocessor on the tow vehicle to accept commands and send them via the data bus to a microprocessor on the trailer. The microprocessor on the trailer then interprets the commands and performs some function, such as to turn on the trailer's brake lights. This trailer-mounted microprocessor could also send status information back to the microprocessor on the tow vehicle via the same (or additional) data bus.
It has been recognized that a multi-purpose data bus can help to simplify tow vehicle and trailer electrical interconnections. This data bus can therefore make a small, low conductor-count, wiring harness perform like a large, high conductor-count, wiring harness. It is therefore possible to accommodate almost all trailer electrical needs in very few conductors, thus reducing the size and complexity of these wiring harnesses. Reducing the complexity of the wiring harnesses and connector plugs, by reducing the number of conductors required, improves the reliability of the wiring harnesses and connector plugs a bit.
There are several drawbacks and limitations to using wiring harnesses and plug connectors for tow vehicle and trailer interconnections. When the tow vehicle is not actively towing, the wiring harnesses are not being used. During this period, the plugs can corrode, become crushed or become severed when left dangling from the hitch and exposed to danger. To avoid dangling, the harness is sometimes wrapped around the hitch itself, but still exposed to eventual damage. This wrapping and unwrapping also causes eventual broken wires, which may lead to a difficult to locate failure. These harnesses and connector plugs also remain visible, especially when not in use. Some items such as boat trailers and campers are, for the most part, infrequently used. Such infrequent use leads to the harness and connector troubles indicated. Frequently operated tow vehicles and trailers may avoid some of the common troubles, but exhibit further problems in that the harnesses and connector plugs are subjected to increased wear and tear. As a result, mating one or more harnesses and connector plugs every time a trailer is connected to a tow vehicle could become a time consuming chore. This chore could be further complicated in low ambient lighting conditions. Additionally, the operator could forget to connect the harnesses before towing, thus posing a safety risk and possibly fines. Worse yet, forgetting to disconnect the harnesses after de-coupling the hitch and hitch receiver, thus damaging the harnesses and connector plugs.
The prior systems have used such transmission media as air-brake lines and dormant conductors in wiring harnesses to create a data bus link between the tow vehicle and trailer. While these systems do help to reduce the complexity of the wiring harnesses and connector plugs, the harnesses and plugs are still required. Since the wiring harnesses and connector plugs are still required, the reliability is not at its peak and the system still suffers the same common ailments of harness and plug systems without a data bus. Although the harnesses and plugs may have been reduced in size and complexity, the mating of these plugs and harnesses still may be quite time consuming. Furthermore, some of these solutions, in particular the solutions using air-brake lines, preclude the system's use in a tow vehicle and trailer configuration without air brakes, such as general boat trailers and camper trailers.